1. Field of the Invention
The present invention relates to a semiconductor device including a printed circuit board on which a semiconductor chip is mounted, and method of manufacturing it. Particularly, the present invention relates to the structure and the shape of an electrode formed on the semiconductor chip, and to a method of manufacturing a semiconductor device including such an electrode. The present application claims priority under 35 U.S.C. § 119 to Japanese Application No. 2002-6786 filed on Jan. 15, 2002, which is hereby incorporated by reference in its entirely for all purposes.
2. Description of the Related Art
In the related art, a semiconductor device which is assembled using a multi chip package is shown in FIGS. 1A and 1B. The FIG. 1A is a cross sectional view and the FIG. 1B is a plane view.
A first semiconductor chip 54 is fixed on a printed circuit board 50 by an adhesive layer 52. A second semiconductor chip 56 is fixed on the first semiconductor chip 54 by an adhesive layer 52. A plurality of electrodes 58 are respectively formed on each surface of the first and second semiconductor elements 54 and 56. A plurality of conductive patterns 60 are formed on the printed circuit board 50, and the conductive patterns 60 are respectively connected with the electrodes 58 of the first semiconductor chip 54 by metallic wires 64. Some of the electrodes 58 of the first semiconductor chip 54, to be connected with the electrodes 58 of the second semiconductor chip 56, have aurous stud bumps 66 on each of their own surfaces in order to absorb the impact generated when the metallic wire 68 is connected to the electrodes 58 of the first semiconductor chip 54. The aurous stud bump 66 is connected with the electrodes 58 of the second semiconductor chip 56 by a metallic wire 68. When the first and second semiconductor chips 54 and 56 are connected with each other through the electrodes 58, at the beginning, a metallic ball 62 which is another edge of the metallic wire 68 is connected to the electrodes 58 of the second semiconductor chip 56, and hereupon, the other edge of the metallic wire 68 is connected to the aurous stud bump 66 on the electrodes 58 of the first semiconductor chip 54. After that, the first and second semiconductor chips 54 and 56 are sealed by a molding resin 70. A plurality of the solder balls are formed on a back surface of the printed circuit board 50 as external connecting terminals.
However, in the above-mentioned semiconductor device, it is necessary that a thickness of the aurous stud bump 66, which is expensive due to the cost of material, is no less than 10 μm in order to absorb the connecting impact generated in wire-bonding between the metallic wire 68 and the electrodes 58 of the first semiconductor chip 54. Also, it takes much time to form a plurality of the aurous stud bumps 66 on the electrodes 58 because the bumps 66 on the electrodes 58 need to be formed one by one in sequence. Furthermore, it takes more areas of the electrodes 58 to form the stud bumps 66 on them.